1. Field of the Invention
The present invention relates to a control apparatus for speedily warming up a catalyst for purification of emissions generated from an internal combustion engine (which will be referred hereinafter to as an engine).
2. Description of the Related Art
Various types of devices have been proposed which control the ignition timing where an engine is started in a cooled state, thereby decreasing the maximum combustion temperature and increasing the temperature of emissions (exhaust gases) from the engine to reduce the hazardous components (HC, NOx) being discharged from the engine. For example, according to the Japanese patent Publication No. 62-39269, the ignition timing is retardation-corrected in accordance with the cooling water temperature when the engine is started in a cooled state, and when the cooling water temperature reaches a predetermined temperature lower than the temperature corresponding to the fully warmed-up state of the engine, the retardation amount is decreased in accordance with the time period that elapses from the time that it reaches the predetermined temperature so as to accelerate the increase in the emission temperature to speedily warm up the catalyst for purifying the emissions.
There is a problem which arises with the aforementioned device, however, in that difficulty is encountered in setting the retardation amount to a large value because the retardation of the ignition timing causes reduction of the engine torque, thereby making it difficult to sufficiently warm up the catalyst due to the increase in the emission temperature resulting from the retardation control thus requiring a long time period until reaching the temperature (the warming-up completing temperature) which allows the sufficient purification of the hazardous components of the emissions through the catalyst. This causes a problem in which the hazardous components are discharged into the atmosphere because of the insufficient purification action of the catalyst until the catalyst temperature reaches the warming-up completing temperature.